Co2 Diffuser

i am looking to buy a Co2 Diffuser because my plants seem to not be getting any Co2 from my fert(plant food) that can keep them lively.
So i am just wondering what is needed for a Diffuser, Obviously to get a ceramic/glass diffuser but what else is needed for it, a air pump?, single tube lining? etc?

It is not likely the CO2 that is the problem with your plants.  Light is the main issue, then nutrients.  Some plants require more (of light and nutrients), others less.  Adding CO2 will not help if the light is too weak to balance it, and the other nutrients are insufficient.
 
If memory serves me, you also have fairly small tanks (20 or 30 gallon?) and in my view CO2 diffusion is wasted money.  I have maintained dozens of planted tanks, including my current 7, for over 20 years without ever adding any form of CO2.  I'd hate to see you wasting money for this and not achieve any benefit.  And then there is the water chemistry aspect of adding CO2 that is another story.
 
Perhaps some photos of the tanks/plants, and some data on your lighting and fertilizers (if any) will help one of us to sort out the likely issue.
 
Byron.

I use a t2 Light thats on for 8-10 hrs during the night, and i use Aqueon Plant food

And on the plant photos they look like they are doing good, but the leaves are coming off to often and have a brownish tint to them(not algae as it doesnt come off)

Can you provide more data on the light?  Type (fluorescent tuber, incandescent [screw-in] bulb, LED, etc), spectrum (the Kelvin or CRI rating), watts.
 
On nutrients, what is the tap water GH?
 
B.

flourescent tube, T8(not T2) 15 Watt full spectrum flouramax Plant growth light

and with the spectrum i assume its 5500K, 93CRI

and the GH is 5, KH is 1.25

OK, I am going to suggest a different tube.  I know there are comments on the Fosters&Smith website from those who say their plants do well, but I am hesitant.  This tube has a Kelvin of 4000K-5000K, according to fosters&Smith, and I consider that low.  I believe this is the same tube that came with my Aqueon 29g tank hood, and it went to recycling after I turned it on.  The problem with these so-called plant or aquarium tubes is the weakness of the light intensity.  I have experimented with several over the past few years, and none were worth it.
 
You would be better with a tube in the 6000-6500K range.  ZooMed make one, called Ultra Sun, that is 6500K.  And there is the Hagen Life-Glo at 6700K.  I use the latter on all my single-tube tanks, but the ZooMed I mentioned is near-equal.  You should be able to find one or both of these in a fish store.  Take the Aqueon tube with you to ensure you get the correct length.  And in T8 of course.
 
These two tubes are high in the red, blue and green.  Red and blue are necessary to drive photosynthesis in aquatic plants, but studies have proven that adding green to the mix does improve the plants' response.  Green does not impact photosynthesis like red and blue, but the added brightness seems to provide the additional intensity.  These tubes are the closest to mid-day sun.
 
The Aqueon liquid fertilizer should be OK; not everything is included, but it has several nutrients and may be sufficient to supplement.  If things don't improve with the new light, we could look at other comprehensive supplements but for the moment I would use what you have.  The GH is fine (this has to do with the so-called "hard" minerals that are present in most tap water, and a GH of 4 or above will be fine in this aspect).
 
On the light, 8 hours should not be too much, but make sure the aquarium receives several hours of total and complete darkness, meaning tank light off and a dark room with no lighting.  This is essential for the fish as well as the plants, to keep the circadian rhythm stable.
 
Byron.

Quick question about the total and complete darkness mentioned by Byron... is the nightlight setting on a regular aquarium light adequate, or does it need to be off and pitch dark?

HarpyFishLover said:

Quick question about the total and complete darkness mentioned by Byron... is the nightlight setting on a regular aquarium light adequate, or does it need to be off and pitch dark?

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It must be complete and total darkness.  This means no ambient room light and no tank lights of any sort.  I'll explain with some detail, taken from an article I authored some time back.
 
Most animals have an internal body clock, called a circadian rhythm, which is modified by the light/dark cycle every 24 hours.  This is the explanation for jet-lag in humans when time zones are crossed—our circadian rhythm is unbalanced and has to reset itself, which it does according to periods of light and dark.  [It is also the cause behind the odd behaviours associated with the change to daylight savings time, minimal as one hour is.]  Our eyes play a primary role in this, but many of our body cells have some reaction to light levels.  In fish this light sensitivity in their cells is very high.
 
Fish eyes are not much different from those of other vertebrates including humans.  Our eyes share a cornea, an iris, a lens, a pupil, and a retina.  The latter contains rods which allow us to see in dim light and cones which perceive colours; while mammals (like us) have two types of cones, fish have three—one for each of the colours red, green and blue.  These connect to nerve cells which transmit images to the brain, and the optic lobe is the largest part of the fish’s brain.  The rods and cones in the fish's eye shift according to the changes in light.  This process is also anticipated according to the time of day; the fish “expects” dawn and dusk, and the eyes will automatically begin to adjust accordingly.  This is due to the circadian rhythm.
 
This is one reason why during each 24 hours a regular period of light/dark—ensuring there are several hours of complete darkness—is essential for the fish.  In the tropics, day and night is equal for all 365 days a year, with approximately ten to twelve hours each of daylight and complete darkness, separated by fairly brief periods of dawn or dusk.  The period of daylight produced by direct tank lighting can be shorter; and the period of total darkness can be somewhat shorter or longer—but there must be several hours of complete darkness in the aquarium.  The dusk and dawn periods will appear to be stretched out, but that causes no problems for the fish.  It is the bright overhead light that is the concern, along with having a suitable period of total darkness.  And the "day" period when the tank lights are on should be one continuous period, not sporadic, and it should be the same every 24 hours or it will impact the circadian rhythm causing more stress.
 
In nature, darkness can vary depending upon the time of year, the latitude, and moonlight.  In the tropical rainforests, darkness is generally pitch blackness, quite unlike anything most of us are used to at night.  Moonlight does not penetrate the forest canopy except in a few places such as the largest rivers that are open, but even here, the fish tend to remain along the banks where the overhanging vegetation is still shading any light.  Even during high noon with a full sun, these parts of the river can be very dimly lit.
 
I mentioned above that fish naturally "expect" the light and dark.  This can be seen even in blind fish.  Pencilfish of the genus Nannostomus have a diurnal pattern; during the darkness, the horizontal lines break up into dashes.  Studies have shown that even in blind fish, this still occurs.
 
Byron.

i had bought the new light for 19$ so i should get it here in a couple days

A note about Aqueon plant food.  I used it in the past on my tank in which I use RO water.  I had inconstant results with it.  It doesn't have copper in it.  When my tanks copper levels were OK I had great plant growth.  However over time with RO water copper levels dropped and eventually plant growth slowed dramatically.   Now most tap water has copper due to the copper pipes in homes.  However now a lot of contractors are using plastic piping.  So your copper levels might or might not be OK.  I have since witched to Flourish Comprehensive which does have copper and my plant growth is more consistent .   
 
How much water do you cycle, how many gallons in the tank,  and how much fertilizer do you apply to your aquarium after the cycle?  Your plants are not growing and if you are not cycling enough water, phosphates could buildup. .High phosphates can slow or stop plant growth.  Another thing to watch out for is over fertilization. If you apply to much fertilizer you might have too much sulfate in the water which for some plants will also slow or stop plant growth.
 
As to CO2, I also don't believe that i your issue.  However instead of adding CO2 you could try increasing tank aeration.  Many people just position the filter output to just cause water movement at the surface.  That is probably enough in most situations.   but if it is not, you could  try positioning your filter output so that the water outflow is above the surface of the water.  This would forcing the water to fall about a inch before hitting the surface.  This would push air bubbles into the tank.  An alternative would be to add a aeration stone and  and air pump to the tank.  If increased aeration doesn't help CO2 deficiency is probably not an issue.  
 
As to lighting, Byron has more experience than I do with Florescent lighting so I would go with his advice.  

i have a air stone already, and its placed under my current(flow) filter so the O2 Bubbles get distributed evenly

for my 20Gal tank i remove maybe 40-50% of the water for a water change, and Adding Copper isnt a option as i have assassin snails and their food(Pond snails) would be harmed/killed, if i add copper it has to be VERY Minute to where it wont kill my Assassin snails

 
 
Copper isnt a option as i have assassin snails and their food(Pond snails) would be harmed/killed

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Seachem flourish comprehensive is only  0.0001% copper.  The bottle Label says "Safe for invertebrates such as shrimp".  I personally have 8 shrimp and 3 nerite snails and  a lot of unwanted pond snails in my aquarium.  So it will not harm your snails.  I would give it a try.  you can get a 50ml supply (about 1 years worth) from amazon for about $12 dollars (excluding shipping).
http/www.amazon.com/Flourish-50-1-7-fl-oz/dp/B0006JLX5G/ref=sr_1_1?ie=UTF8&qid=1459099764&sr=8-1&keywords=flourish+comprehensive+50ml
 

 
 
my 20Gal tank i remove maybe 40-50% of the water for a water change

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You are cycling enough water "about 10 gallons".  So you should be adding 10ml of your current fertilizer.  However since your plants are currently not doing well i would cut that down to 5ml for now.  If you change your fertilizer be sure to adjust the dose according to the bottles instructions.
 

 
 
i have a air stone already, and its placed under my current(flow) filter so the O2 Bubbles get distributed evenly

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You have good aeration so I see no need to change this.  Based on everything I see lack of nutrients (possibly copper) is your problem, not CO2

i add 4-5Mls per day, as i prefer smaller doses that add up to the 20Gal per week

 
 
 add 4-5Mls per day, as i prefer smaller doses that add up to the 20Gal per week

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That would be fine if you were replacing 20 gallons of water a week. But you are only  cycling 10 gallons a week, not 20. You are overdosing on fertilizer.    Also in my experience one dose per week is all that is needed.  Healthy plants will not grow fast enough in one week to consume  all of the 20ml of fertilizer. The does should be based on the amount of water you  put in the tank per week, not the size of the tank. 

i just go by the instructions on the bottle